Hematopoietic cells circulating in blood and found in other tissue areas are produced by stem and progenitor cells. A viable alternative to bone marrow as a source of stem/progenitor cells is human umbilical cord blood at least as assessed by in vitro colony assays. Cord blood has recently been used in an HLA-matched sibling setting in a number of cases and in a partially HLA-matched sibling setting in one case to successfully engraft the hematopoietic systems of children with Fanconi anemia and leukemia. Other disorders including aplastic anemia, Wiskott Aldrich syndrome and an x-linked lymphoproliferative disorder have also been transplanted with HLA-matched sibling cord blood, but at the time of this writing information is not available yet on engraftment. Additionally, intriguing reports from China mention use of mixtures of unmatched unrelated cord blood transplants. It is felt that the time is now right for a full indepth meeting on the biology and transplantation capability of umbilical cord blood in order to assess the broadness of applicability of this relatively new form of treatment. It is proposed to have a conference in this area which includes the following sessions: 1) Background/History; 2) Clinical Experiences; 3) Cord Blood Stem/Progenitor Cells which would include growth of these cells in short vs. long term -cultures, proliferative vs. self-renewal capacity of these cells, enrichment/purification of the cells, animal models. to study their growth in vivo, and expansion of these cells in vitro and in vivo; 4) Immunological Reactivity which includes assays to assess graft vs. host and graft vs. leukemia potential of these cells; and 5) Future of cord blood transplantation which would include broadness of applicability, optimization of cord blood collections, in utero tissue typing and disease markers, and cord blood banking. The conference will be interactive with ample time for discussions after each oral presentation and with round table workshop type discussion groups. The proceedings of this meeting will be published and will serve as a source book detailing the past, present, and future aspects of this new and very exciting area of investigation. It is believed that such a meeting will bring new investigators into this area of research, will intensify the efforts of those investigators already working in this area, will help to define the best uses for cord blood, and will hasten the establishments of allogeneic and autologous cord blood banking.